The present invention relates to deflection plates for an electrostatic ink-jet printer.
In order to print the ink-dot images at a high speed and with a higher degree of resolution, multi-nozzle ink-jet print heads with a large number of nozzles with very fine diameters have been increasingly developed. However, obviously a nozzle of an extremely fine diameter produces an ink drop of a corresponding size so that its kinetic energy is low and consequently it is easily susceptible to aerodynamic and electrostatic disturbance while it is in flight. To the same ends, there has been a tendency toward the arrangement in which the trajectory of the ink drops is selected closer to the deflection plates. However, when the trajectory is made too close to the deflection plates so that the boundary layers of the air streams produced by the flight of ink drops reaches the surfaces of the deflection plates, turbulent flows are produced, so that the ink drops are deflected from the intended trajectory and consequently the misplacement of ink drops results which causes misregistration, merging and scattering of ink drops on a recording paper, degrading the quality of printed images.
When a pair of the deflection plates are disposed in parallel with each other, the electrostatic lines are concentrated at the entering and leaving ends, so that the gradient of the electric field becomes greater and consequently the ink drops are deflected at an angle greater than the desired deflection angle, so that the misplacement of ink drops also results.